BigJohn99

I was on the verge of using a heat gun to strip the paint from an old Motobecane thin-walled steel frame, when I thought about heat-treated steel etc, and had second thoughts. Does anyone know for sure if a heat-gun can damage a steel frame, or change the heat-treated properties? I'm not keen on using paintstripper.

Thank you.

eddubal

Theoretically, yes / practically, no. Have fun stripping away. Just don't think that the fumes given from the melting paint are harmless. Either way, make sure you have adequate ventilation and preferably a respirator.

ultraman6970

paintstripper and use car paint, rattle can wont last long at all.

zaskar.le

Unless your going to hold heat gun to frame on its highest heat for a long while it's highly unlikely to do any damage unlike paint stripper which is highly toxic esp bad for guys hoping to father children.check net for contents of p/s! think you will soon leave it in it's can or on shelf!.
On way you can strip it is if you have a drill and a angle grinder get a zip wheel for them and wire brush that will remove all the paint and not metal.

MikeX

A few comments:

Your Motobecane is probably a lugged frame. That means that the lugs and tube ends have been brazed, which is to say they have already exposed to a temperature over 1000° F.

Almost all steel bicycle tubing for lugged frames is designed to be brazed (exposed to 1000° F plus) with minimal decrease in mechanical properties.

At 1000° F metal glows a dull red glow that can be seen in a darkened room.

In my experience, most paints soften and discolor at 300° F and are mostly goo at 500° F.

Though I suggest that you check the maximum temperature your heat gun can produce, perhaps with an oven thermometer, you have a huge safety margin between the 500° F where the paint comes loose and the 1000° F plus where you start having a significant effect on the mechanical properties.

BigJohn99

Thanks very much chaps. In the end I used a combination of all three methods. I did the big areas with a angle grinder stiff metal brush wheel, but this a bit rough with the edges of the lugs and braze-ons. This is the kind of thing that looks crap when you paint it. I then decided to use paintstripper for the tricky bits, remembered why I hate with the made a horrible smelly mess that ensued, then plumped for the heat gun. This is by far the best method, and almost as fast as the wire brush. The frame has a lot of sentimental value, so I wanted to be easy on it if possible.

BigJohn99

eddubal - Good advice, it certainly does give off some fumes.

BigJohn99

zaskar.le - Good advice, thanks. Happily I have enough children, although lung cancer and organ damage I can do without.

BigJohn99

MikeX - That's the answer I was looking for, thanks.